Energy efficiency in small-scale biointensive organic onion production in Pennsylvania, USA

Modern agriculture relies heavily on fossil energy for food production. Reducing fossil energy and replacing that energy with renewable energy is critical in attaining a sustainable food system. Hand-scale intensive food production offers a reduction in fossil energy and an increased use of renewable human-based energy. Using biointensive production techniques, onions (Allium cepa) were grown in Pennsylvania, USA. A life-cycle analysis was performed to monitor energy utilization. Individual human labor tasks were evaluated using the factor method. This method accounts for the type and duration of physical activity. The average yield of eight onion varieties utilizing biointensive production in standard-sized beds (9.3 m(2); 100 ft(2)) was 160.2 kg. The US average for mechanical onion production is 46.1 kg/9.3 m(2) (100 ft(2)). The energy efficiency ratio, specific energy and energy productivity were 51.5, 0.03 MJ kg(-1) and 32.2 kg MJ(-1) (MJ = megajoule), respectively. When defined within common boundaries, these three relationships: energy input, energy output and yield productivity allow researchers, farmers and policy-makers to select production systems and/or practices that better manage fossil and renewable energy for food production. Current mechanized agriculture has an energy efficiency ratio of 0.9. With most energy being supplied by fossil fuels. The energy efficiency for biointensive production of onions in our study was over 50 times higher than this value (51.5) and 83% of the total energy required is renewable energy. Biointensive production offers a viable energy use alternative to current production practices and may contribute to a more sustainable food system.